Fading in
Abstract
Patient H.M. can form new memories and maintain them for a few seconds before they fade away. From a neurobiological perspective, this amnesia is usually attributed to the absence of memory consolidation, that is, memory storage. An alternative view holds that this impairment reflects that the memory is present but cannot be retrieved. This debate has been unresolved for decades. Here, we will consider some of the arguments that make it so difficult to resolve this issue. In addition, some recent work will be discussed that has gone beyond the shortcomings of previous experimental approaches to strongly suggest that amnesia can be due to a retrieval impairment that can be overcome with a reminder—an example of memories fading in. Finally, this review will suggest some strategies for resolving this debate.
Footnotes
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↵1 Corresponding author.
↵1 E-mail karim.nader{at}mcgill.ca; fax (514)-398-4896.
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Article is online at http://www.learnmem.org/cgi/doi/10.1101/lm.350906
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2 Because of all of these issues surrounding amnesia and the lack of consensus on its nature, K.N. took an agnostic view of amnesia (Debiec et al. 2002). Given that consolidation and reconsolidation are both time-dependent memory stabilization processes and there are many commonalities in mechanism, then it seemed parsimonious to view the nature of amnesia for new learning and reactivated memories as being the same. Furthermore, K.N. is open to amnesia being either a storage or retrieval impairment. Amnesia for new information is typically discussed in terms of a blockade of consolidation. Therefore, in line with this tradition, K.N. has discussed amnesia for reactivated memories as a blockade of reconsolidation. This is admittedly a slightly confusing position, but the other options were a view that cannot be proven and one that cannot be refuted.
- Copyright © 2006, Cold Spring Harbor Laboratory Press
